The present invention relates to a vehicle seat, which is used, for example, as a front or rear seat of an automobile and prevents a submarine phenomenon at the time of a head-on collision.
The driver or a passenger of an automobile should fasten his or her seat belt and wear it properly. If the seat belt is not worn properly, it may disengage from the waist of the driver or passenger at the time of a head-on collision, and the driver or passenger may be thrown out of the seat belt. This is generally referred to as a "submarine phenomenon" or simply "submarine." If this phenomenon occurs, the buttocks or legs of the driver or passenger may be thrown forward, with the seat belt in engagement with the abdomen. In some cases, the legs may collide with the installment panel, which is located in front of the driver or passenger.
To prevent this submarine phenomenon, a seat frame having a projection or a panel at the front end is known in the conventional art. A submarine preventing mechanism which mechanically raises the front end portion of a seat is also known. In addition, a submarine preventing mechanism that employs an air bag (Jpn. Pat. Appln. KOKAI Publication No. 5-229378) and a submarine preventing mechanism that utilizes a gunpowder actuator to raise the front portion of a seat (Jpn. Utility Model Appln. Kokoku Publication No. 7-27240), are proposed.
However, the conventional structure that employs a projection or a panel cannot reliably prevent a submarine, since the frame is likely to bend in the form of "V." The conventional structure that employs an air bag and the structure that mechanically raises the front portion of a seat cushion may be reliable in performance, but they are inevitably complex. In other words, they employ a large number of elements and are not compact in size. Hence, they cannot be easily arranged in the restricted space inside a seat cushion, resulting in difficulty in the determination of layout. In this manner, the conventional structures are not suitable as commercial products.